It looks like as if the alias part was missing, check your httpd.conf or apache2.conf
and look if you have this line
Alias /icon "/home/admispconfig/ispconfig/tools/awstats/wwwroot/icon/"
And yes if you could send me the diff, I will have a look at It. Maybe when we have recieved a little bit more feedback about this installer we could try to include it in the dev branche of ISPConfig, if Till and Falko agree.